1. Field of the Invention
The present invention relates to devices for the anterior fixation of the spine. In particular, the present invention relates to an anterior adherent plate for the fixation of thoracic and lumbar vertebra.
2. Description of the Related Art
Trauma, burst fractures (typically in the T11, T12, L1 or L2 vertebrae), tumors, severe disc degeneration, and anterior fusion following multiple posterior operations are some of the causes of anterior thoracolumbar spinal instability. Anterior treatment of thoracolumbar spinal instability typically involves the use of anterior fixation devices including (i) connective structures, such as rods or plates, that extend between the vertebrae, and (ii) fasteners that engage the appropriate vertebra to affix the connective structures to the vertebra.
Current anterior fixation devices allow for semi-rigid stabilization through rod and staple constructs, or rigid immobilization with locking plate/screw devices. Various devices suitable for anterior thoracolumbar fixation are known. U.S. Pat. Nos. 6,228,085, 5,603,713, 5,601,553, 5,486,176 and 5,324,290 and U.S. Patent Application Publication No. 2004/0210217 describe bone fixation systems which include a plate and screws. Synthes® sells an anterior thoracolumbar locking plate system which employs a rigid screw and plate construct to form a locked plate. Medtronic® sells the Vantage™ anterior fixation system which includes a plate and screws. DepuySpine™ sells the M-2™ anterior plate system and the Profile® anterior fixation system which both include a plate and screws. DepuySpine™ also sells the Expedium™ spine system that utilizes a staple, screw and rod construct to provide a semi-rigid construct that enables a more custom fit of the implant. Its staple and screw interface allows a closer approximation of the implant to the spine but at the expense of more moving parts and less rigidity than a standard plate.
However, existing technologies may not provide rigid fixation and may not be appropriate for situations where there may be a need for prolonged rigid support such as in a milieu of delayed healing potential or severe spinal instability. Also, existing implants are non-anatomic and often only loosely approximate the patient anatomy resulting in a poor-fitting implant.
Accordingly, there is a need for an improved anterior plate for the fixation of thoracic and lumbar vertebra.